Make KeyboardInterrupt catch more aggressive

Fixes: #186
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

src/python/bcc/__init__.py

@@ -653,6 +653,7 @@ class BPF(object):
         fields (task, pid, cpu, flags, timestamp, msg) or None if no
         line was read (nonblocking=True)
         """
+        try:
             while True:
                 line = self.trace_readline(nonblocking)
                 if not line and nonblocking: return (None,) * 6
@@ -665,6 +666,8 @@ class BPF(object):
                 cpu = cpu[1:-1]
                 msg = line[ts_end + 4:]
                 return (task, int(pid), int(cpu), flags, float(ts), msg)
+        except KeyboardInterrupt:
+            exit()
 
     def trace_readline(self, nonblocking=False):
         """trace_readline(nonblocking=False)
@@ -693,6 +696,7 @@ class BPF(object):
         example: trace_print(fmt="pid {1}, msg = {5}")
         """
 
+        try:
             while True:
                 if fmt:
                     fields = self.trace_fields(nonblocking=False)
@@ -702,6 +706,8 @@ class BPF(object):
                     line = self.trace_readline(nonblocking=False)
                 print(line)
                 sys.stdout.flush()
+        except KeyboardInterrupt:
+            exit()
 
     @staticmethod
     def _load_kallsyms():